00:01
Here in this problem we have given second theta is equal to minus 13 upon 12 where theta is greater than 90 degree and smaller than 180 degree.
00:15
And we are asked to find the exact value of sine 2 theta, cosine 2 theta and tangent 2 theta.
00:21
So here we have second theta is equals to minus 13 upon 12.
00:25
And we know that second theta is a reciprocal of cosine theta.
00:33
So from here we get cosine theta.
00:38
Is equal to minus 12 upon 13.
00:42
Now for calculating the value of cosine 2 theta we will apply the formula.
00:49
Cosine 2 theta is equal to 2 into cosine square theta minus 1.
00:55
By substituting the value of cosine theta in this formula we get cosine 2 theta is equal to 2 into minus 12 upon 13 whole square minus 1.
01:12
It would be equal to 2 into 114 upon 14.
01:19
169 minus 1.
01:22
By simplifying it we get cosine 2 theta is equal to 288 minus 169 upon 169.
01:33
By simplifying it we get cosine 2 theta is equals to 119 .19 upon 169.
01:43
Now in order to find the value of sine 2 theta first of all we will find the value of sine theta as we know that 5 square theta is equal to 1 minus cosine 2 theta upon 2...